Our specific objectives for the coming year are directed to the respiration and bioenergetics of cancer cells, particularly the stoichiometry and efficiency of energy coupled H ion movements, ATP synthesis, and Ca2 ion transport: (1) We propose to continue our analysis of the stoichiometry of H ion ejection by respiring tumor mitochondria, particularly the H ion/O ratio of the cytochrome oxidase reaction, using a new type of oxygen electrode developed in this laboratory and fast recording techniques, using a recording cathode ray oscillograph. (2) We shall also determine the H ion/ATP stoichiometric ratio during the breakdown and synthesis of ATP by the F0F1ATPase activity of intact tumor mitochondria. (3) We propose to determine the stoichiometric relationships between the movement of ATP, ADP, and phosphate across the mitochondrial membrane during both oxidative phosphorylation and energy dependent reversal of electron transport. (4) In selectively permeabilized intact tumor cells we propose to determine the H ion/O ratio of mitochondiral electron transport in situ, the P/O ratio of oxidative phosphorylation in situ, and the stoichiometry of Ca2 ion transport. (5) We propose to test further our hypothesis, based on evidence derived from our earlier work, that the rate of ATP formation in intact tumor cells is depressed because of an abnormal affect of intramitochondrial Ca2 ion on ATP translocation or synthesis.